Satanic Panic
题意翻译
二维平面上有$n$个点，其中第$i$个点的坐标是$(x_i,y_i)$。
你想找出来五个点，使得这五个点形成一个五角星，五角星定义为五条对角线互相交于五个点。
求找出来五个点的方案数。
题目描述
You are given a set of $ n $ points in a 2D plane. No three points are collinear.
A pentagram is a set of $ 5 $ points $ A,B,C,D,E $ that can be arranged as follows.  Note the length of the line segments don't matter, only that those particular intersections exist.
Count the number of ways to choose $ 5 $ points from the given set that form a pentagram.
输入输出格式
输入格式
The first line contains an integer $ n $ ( $ 5 \leq n \leq 300 $ ) — the number of points.
Each of the next $ n $ lines contains two integers $ x_i, y_i $ ( $ -10^6 \leq x_i,y_i \leq 10^6 $ ) — the coordinates of the $ i $ -th point. It is guaranteed that no three points are collinear.
输出格式
Print a single integer, the number of sets of $ 5 $ points that form a pentagram.
输入输出样例
输入样例 #1
5
0 0
0 2
2 0
2 2
1 3
输出样例 #1
1
输入样例 #2
5
0 0
4 0
0 4
4 4
2 3
输出样例 #2
0
输入样例 #3
10
841746 527518
595261 331297
-946901 129987
670374 -140388
-684770 309555
-302589 415564
-387435 613331
-624940 -95922
945847 -199224
24636 -565799
输出样例 #3
85
说明
A picture of the first sample:  A picture of the second sample:  A picture of the third sample: 